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Join Date: May 2001
Location: Peoples Republic of Long Beach, NY
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vacuum crashes when accelerating

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Ronin LB
'77 911s 2.7
PMO E 8.5
SSI Monty
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Old 04-17-2005, 08:08 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #41 (permalink)
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Join Date: Mar 2005
Location: iowa
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Was away for the wekend, but will start working on the SC again tomarrow.

I will go after recommended areas:

1. Injectors - checking for even flow and a good pattern.
2. Distributor advance/retard via the two vacuum lines.

How do I check for correct operation in response to the vacuum sources?

I have validated the retard side, I believe. The side twords the fan. I have not checked out the other side of the vacuum actuator.

Dizzy?

Thank you for the assistance and information.

Marlin

Gunter,

On SCs with O2 sensor: The frequency valve duty cycle can be measured with a dwell meter via the green/white wire in the engine compartment. The valve is controlling mixture at all times. The valve drive is 50 percent duty base (open loop), 65 percent below 15 degrees C and at WOT. Closed loop, the O2 sensor is read and drives the valve to achieve Lambda=1. Below approx. 50 percent leans the mixture, above richens. On the meter, a dwell of 45 is 50 percent duty cycle on the 4 cylinder scale; 30 dwell is 50 percent for the 6 cyl, etc.
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82 911SC
Old 04-18-2005, 03:16 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #42 (permalink)
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Location: BC,Southern Interior ,Canada
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Garage
fixed yet?
what was the problem?
Old 05-29-2005, 06:10 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #43 (permalink)
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lonewolf

The main fix was changing the plugs. Most, if not all, had an effective gap of almost double the spec. The long version is above on page 2.

I am still slowly sorting through the rest of the system. I will be adding new O-rings to the injectors, etc.

Overall, the plugs improved things greatly and appeared to be the source of the detonation and the stumle (bog) as the motor loaded up.

Thank for the inquiry.

Marlin

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82 911SC
Old 05-30-2005, 06:30 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #44 (permalink)
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